Crown for tooth enamel erosion?

[dar]

I am 42 years old. Recently I noticed my two upper front teeth (central incisors) had become grey. Around 25% of the teeth area from the top had become grey and touching them with fingernail indicated a noticeable dip in the teeth. However there was absolutely no pain or changes in teeth sensitivity. Dentist said that my tooth enamel has eroded and recommended crown for both teeth. Was very expensive, but I went ahead with the procedure yesterday. Currently I have temporary crowns until the porcelain crows are manufactured and fitted in 1-2 weeks time. My teeth were generally health so far, and this is the first time I had anything done to it other than regular cleaning. I regret of not having taken second opinion for two reasons- 1. Crown involves such significant filing of the original teeth- I hadn't realized the extent to which it would be filed 2. Price. My question is, does crowns seem reasonable for my symptoms? Would a dental bonding (or some other procedure) have been an alternative procedure to consider, just from the description of the symptoms? How long might the crowns last? Is it possible to last a lifetime? I know its too late to undo anything at this point, but would like to get some advice for any future problems that might be similar.